From 9a54fb31343362f93680543e37afc14484c185d9 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Mon, 24 Feb 2025 13:37:04 +0100 Subject: [PATCH] x86/cfi: Add 'cfi=warn' boot option Rebuilding with CONFIG_CFI_PERMISSIVE=y enabled is such a pain, esp. since clang is so slow. Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Ingo Molnar Reviewed-by: Kees Cook Link: https://lore.kernel.org/r/20250224124159.924496481@infradead.org --- arch/x86/kernel/alternative.c | 3 +++ include/linux/cfi.h | 2 ++ kernel/cfi.c | 4 +++- 3 files changed, 8 insertions(+), 1 deletion(-) diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c index 247ee5ffbff4..1142ebd3bb49 100644 --- a/arch/x86/kernel/alternative.c +++ b/arch/x86/kernel/alternative.c @@ -1022,6 +1022,9 @@ static __init int cfi_parse_cmdline(char *str) cfi_mode = CFI_FINEIBT; } else if (!strcmp(str, "norand")) { cfi_rand = false; + } else if (!strcmp(str, "warn")) { + pr_alert("CFI mismatch non-fatal!\n"); + cfi_warn = true; } else { pr_err("Ignoring unknown cfi option (%s).", str); } diff --git a/include/linux/cfi.h b/include/linux/cfi.h index f0df518e11dd..1db17ecbb86c 100644 --- a/include/linux/cfi.h +++ b/include/linux/cfi.h @@ -11,6 +11,8 @@ #include #include +extern bool cfi_warn; + #ifndef cfi_get_offset static inline int cfi_get_offset(void) { diff --git a/kernel/cfi.c b/kernel/cfi.c index 08caad776717..19be79639542 100644 --- a/kernel/cfi.c +++ b/kernel/cfi.c @@ -7,6 +7,8 @@ #include +bool cfi_warn __ro_after_init = IS_ENABLED(CONFIG_CFI_PERMISSIVE); + enum bug_trap_type report_cfi_failure(struct pt_regs *regs, unsigned long addr, unsigned long *target, u32 type) { @@ -17,7 +19,7 @@ enum bug_trap_type report_cfi_failure(struct pt_regs *regs, unsigned long addr, pr_err("CFI failure at %pS (no target information)\n", (void *)addr); - if (IS_ENABLED(CONFIG_CFI_PERMISSIVE)) { + if (cfi_warn) { __warn(NULL, 0, (void *)addr, 0, regs, NULL); return BUG_TRAP_TYPE_WARN; } -- 2.25.1